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HERE IS THE LINK TO THE POST:

https://www.kloia.com/blog/reinvent-2023-recap

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Surprisingly my 4-year-old blog post is still on Google #1 Page in organic search, doesn’t it deserve an update?  Just updated with minor changes:

• Windows container support
• Forrester report update

Here is the latest version:

https://www.kloia.com/blog/openshift-vs-rancher

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How will the pandemic affect geo-based salary policies?

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[TR] Yeni yazım: Relocation mı yoksa TR den yurtdışına remote mu?

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I have published an article regarding our Dojo approach at kloia: Click here!

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Recently i had to dig into a JVM thead wait/blocking/locking troubleshooting and i decided to write down my notes just for future reference for myself and for you!:)

Pre requirements to be known:

1. JVM Memory Space: This is divided to 3 following parts:

1.a Native Heap/Code Cache:  

– Byte Code for JIT

– Native code which are already converted from Byte Code

– Mmap(Memory Map) files

1.b PermGen/Metaspace: Beginning from Java8, this area has no upper limit in order to avoid OutOfMemory errors. Operating System will use SWAP area(Virtual Memory) if the usafe goes beyond Physical Memory.

1.b.i. Size: This is defined my XX parameter 

1.b.ii. Heap Structure: The following are stored under Metaspace:

• Class Definitions Metadata: Class Name, Object Arrays, Internal Object used by JVM, optimization information
• Static Member Variables (Variable itself / Object Reference) 

 1.c Heap: All runtime created stateless&stateful objects, app data, caches are stored in Heap.

1.c.i. Heap Size: Heap size is defined by two parameters:

• Xms(Initial Memory Allocation) 
• Xmx(Maximum Memory Allocation) 

1.c.ii. Heap Structure: Heap is divided into following spaces:

• Young: Divided into 2 parts:
  • Eden: First space used when the object is created.
  • Survival: The objects which are survived from GC(Garbage Collection) are stored on so called S0/S1
• Tenured/OldGen: Objects reacted to max tenured threshold are moved to this space

Here is the model as a schema:

Ref. schema

2. Footprint Requirement: This can be calculated considering the following formula:

• Number of ear, jar, war files that the single JVM process will handle
• Number of Java classes to be loaded during runtime
• Data cache(file, DB …) footprint
• Number of threads that are allowed to be created

Usually heap size 3-4 GB. is a starting point….

3. GC(Garbage Collection): Minimizing the GC frequency is a key factor for performance. Concurrent users and requests generate JVM GC HeartBeat. The frequency should be monitored. 

4. Young vs Tenured: The typical ratio is 1/3, for example if you have 4 GB. Heap, 1GB for Young, 3GB for Tenured is expected. But this is totally depent to your business rules and traffic patterns. 

5. Thread Dump Analyzer: There are various tools that you can use, the ones that i prefer are:

• https://spotify.github.io/threaddump-analyzer/
• http://fastthread.io/

Use XX:+HeapDumpOnOutOfMemoryError in order to create the Heap Dump in case of OutofMemory.

Here are the most popular focus areas that should be analyzed:

• Memory Leak
• Too many open files
• CPU usage
• Deadlocks
• ClassNotFoundException
• NoClassDefFoundError

As a last experience, there is an intersting jar which makes fullGC every 300 sec.:

https://github.com/jelastic-jps/payara/tree/master/payara-micro-cluster 

That can be considered for non performance required applications…. 

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Google recently announced that, Chrome will alert “NOT SECURE” for the websites not running under HTTPS:
Starting October 2017, Chrome (version 62) will show a “NOT SECURE” warning when users enter text in a form on an HTTP page, and for all HTTP pages in Incognito mode.
In case you have a WordPress site, there are 2 main ways to do that:
1- Converting WordPress to HTTPS mode:
1-a: Change the site URL: The siteurl can only be changed by command line. Find the wp-config.php and update it.
1-b: Change the existing http links: Go to DB and update the links. Beside in case there are plugins which inject their code seperately, you need find all. This is very painful!
1-c: Create a SSL certificate and verify it on a certificate authority.
2- Keeping WordPress a usual and use CloudFlare:
2-a Force HTTPS

2-b Enable HTTPS Rewrite: This is the crucial point. By that, you do not need to edit WordPress http links, as CloudFlare will be replacing them on the fly! (In case you are not under HSTS, it will not replace image links)

2-c Now you should see that links except images are not converted on the fly. Go to https://hstspreload.org and register your domain for HSTS.

**** Be careful! All subdomains and subsubdomains from now on should work under https! ****

So check all your DNS records. With Coudflare, you are lucky, if traffic passes via CloudFlare, it will a common SSL certificate

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Here is my latest kloia blog post: 

https://blog.kloia.com/rancher-on-google-cloud-with-cloud-sql-as-db-4775326f7bab